Systems and Methods for Integrated Resputtering in a Physical Vapor Deposition Chamber

ABSTRACT

Physical vapor deposition systems are disclosed herein. An exemplary physical vapor deposition system includes a target, a collimator, a power source system, and a control system. The power source system is configured to supply power to the collimator and the target. The control system is configured to control the power source system, such that the collimator is bombarded with noble gas ions during a sputtering process and the target is bombarded with metal ions during a re-sputtering process, wherein the collimator functions as a sputtering target during the sputtering process and as the collimator during the re-sputtering process.

This is a continuation application of U.S. patent application Ser. No.14/162,507, filed Jan. 23, 2014, now U.S. Pat. No. 9,887,072, the entiredisclosure of which is incorporated herein by reference.

BACKGROUND

The semiconductor integrated circuit industry has experienced rapidgrowth in the past several decades. Technological advances insemiconductor materials and design have produced increasingly smallerand more complex circuits. These material and design advances have beenmade possible as the technologies related to processing andmanufacturing have also undergone technical advances. In the course ofsemiconductor evolution, the number of interconnected devices per unitof area has increased as the size of the smallest component that can bereliably created has decreased.

One commonly used technique employed to form material layers oversemiconductor wafers is physical vapor deposition, which includes thetechnique of sputtering. In sputtering deposition, a plasma is used toexcite ions, typically of a noble gas, to facilitate forceful collisionswith a target. Atoms of the target are knocked free by the collidingions and then condense on the exposed surface of a semiconductor waferforming a thin layer or film of the target material. Some other PVDchambers may also be used in an etching process by exciting ions, noblegases or metal ions, and generating collisions with the layer to beetched on the semiconductor wafer. As the feature size has decreased,providing sputtered material layers with even coverage on the featureson a semiconductor wafer has become increasingly difficult.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are better understood by reference tothe accompanying figures. It is emphasized that, in accordance with thestandard practice in the industry, various features are not drawn toscale. In fact, the dimensions of the various features may bearbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a cross-sectional diagram of a material layer depositionchamber according to aspects of the present disclosure.

FIG. 2 is a flowchart of a method depositing a material layer on asemiconductor wafer according to aspects of the present disclosure.

Aspects of the present disclosure may be best understood by viewing theaccompanying figures with reference to the detailed description providedbelow.

DETAILED DESCRIPTION

The following disclosure provides different embodiments, or examples,for implementing different features of the disclosure. Specific examplesof components and arrangements are described below to simplify thepresent disclosure. These are, of course, merely examples and are notintended to be limiting.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. For example, if the device is turned over, elementsdescribed as being “below” or “beneath” other elements or features wouldthen be oriented “above” the other elements or features. Thus, theexemplary term “below” can encompass both an orientation of above andbelow. The apparatus may be otherwise oriented (rotated 90 degrees or atother orientations) and the spatially relative descriptors used hereinmay likewise be interpreted accordingly.

Referring now to FIG. 1, a physical vapor deposition system 100 that iscapable of performing both deposition and etch processes is illustratedin cross-section. The deposition chamber 100 has a containment shield102 that forms a chamber 104, including an upper chamber or portion 104Aand a lower chamber or portion 104B. The upper and lower portions 104Aand 104B are separated by a collimator 106. The collimator 106 is astructure that serves to channel sputtered atoms or molecules bylimiting the available paths from a target 114 to a wafer 108 undergoingprocessing. The collimator 106 is open on top and on the bottom, andcomprises a plurality of channels therethrough, the dimensions andgeometry of the channels limiting available paths to material passingthrough the collimator. In some embodiments, individual channels may behexagonal as seen from above, giving a “honeycomb” pattern to thecollimator 106. Other embodiments of the collimator may have othershapes and patterns.

The wafer 108 is supported and brought into position in the lowerchamber 104B by a wafer pedestal 110. In some embodiments, the waferpedestal 110 is an electrostatic chuck, or e-chuck. Clamps (notdepicted) may be positioned over the edges of the wafer 108 to helpsecure it in place. The wafer pedestal 110 may have a temperaturecontrol and maintenance system incorporated therein that allows the atemperature of the wafer 108 to be controlled. For example, the waferpedestal 110 may be used to cool the wafer 108 as the chamber 104 may beheated for and by the production of a plasma therein. Regulating thetemperature of the wafer 108 may improve characteristics of thedeposited material layer and increase the deposition rate by promotingcondensation.

Opposite the wafer 108 and the wafer pedestal 110 and above the upperchamber 104A there is a target carrier structure 112 that supports atarget 114. The target carrier structure 112 secures the target 114during operation of the deposition system 100. The target 114 is a pieceof material from which the material layer on the wafer 108 is to beformed. The target 114 may be a conductive material, an insulatingmaterial, or may be a precursor material that reacts with a gas to forma molecule from which the deposited material layer is made. For example,a metal oxide or metal nitride may be deposited using a metal target 114that does not include oxygen or nitrogen.

A number of power supplies are provided in the deposition system 100 inorder to generate and control the plasma within the chamber 104 and todirect the sputtering and etching, or resputtering, as desired. A directcurrent (DC) power supply 120 is coupled to the target carrier structure112 to supply DC power to it. A radiofrequency alternating current (RF)power supply 122 is coupled to the wafer pedestal 110. In someembodiments, an RF power supply is also provided to the target carrierstructure 112 in addition to the DC power supply 120. Additionally, atleast one power supply is provided to the collimator 106. In theillustrated embodiment, a DC power supply 124 and an RF power supply 126are both coupled to the collimator 106.

As illustrated, both the target 114 and the collimator 106 are made fromthe same material, copper. In conventional deposition systems,collimators, when present, are usually made from aluminum or stainlesssteel. In some embodiments, the collimator 106 may be made from aninterior core structure with a layer of copper deposited thereon, inothers, the collimator 106 is formed entirely from copper.

As illustrated in FIG. 1, the deposition system 100 further includes anumber of magnets. The magnets may include lateral magnets 130 and 132.The lateral magnets 130 and 132 are positioned within the depositionsystem 100 outside the containment shield 102 and may be coil magnets.Additionally, a magnetron 134 is provided over the target carrierstructure 112. The magnetron 134 provides a magnetic field to thechamber 104, particularly the upper chamber 104A, that can facilitatethe control and use of the plasma.

In use, the deposition system 100 can be used for sputtering depositionand for resputtering or etching. For example, during a depositionprocess, the collimator 106 may be used as a sputtering target, insteadof the target 114. To do this, the DC power supply 120 may be turned offto supply no power to the target 114. An RF bias is applied to the waferpedestal 110. This RF bias may be less than about 500 W. RF and DC poweris supplied to the collimator 106 by the RF power supply 126 and the DCpower supply 124. In some instances, only the RF power is supplied tothe collimator 106. Thus, the DC power supply 124 may supply from 0 toabout 10 kW. The RF power supplied to the collimator is about 1 kW ormore.

The power provided by the DC and RF power supplies is controlled by acontrol system 140, which includes one or more processors incommunication with memory. The memory may include process recipes thatare pre-programmed for use in device fabrication. The memory may containinstructions that describe and implement the recipes. The processors arecommunicatively coupled to the power supplies and to a plurality ofsensors in the deposition system 100. The sensors may includetemperature sensors, pressure sensors, position sensors, field sensors,and others.

During the sputtering process, the pressure within the chamber 104 ismaintained at a low level. For example, the pressure may be in a rangefrom about 10 to about 150 mTorr. A gas and pressure system 142 isincluded as part of the deposition system 100. The gas and pressuresystem 142 includes valves, conduits, and pressure and flow sensors tocontrol pressure within the chamber 104, to introduce reactant gases,and to remove exhaust gases. The gas and pressure system 142 is incommunication with the control system 140.

During this sputtering process Ar+ ions may be used to free copper atomsfrom the collimator 106 to condense on the wafer 108.

The deposition system 100 may also be used for etching or resputteringusing metal ions, such as copper ions. This may be done by using thecontrol system 140 to set the DC supply 120 to provide about 20 kW ormore to the target carrier structure 112 and the target 114. The DC andRF power supplies 124 and 126 may be turned off so that no power issupplied to the collimator 106. And the RF bias applied by the RF powersource 122 to the wafer pedestal 110 is more than about 500 W. Thus, thecollimator 106 may function as a collimator only, and not as acollimator and target during a metal ion etch process, such as a copperion etch process. The pressure maintained in the chamber 104 by the gasand pressure system 142 is less than about 1 mTorr.

Both the deposition process and the resputtering process may be used inthe formation of a single material layer on the wafer 108. By enablingboth processes in the deposition system 100, the material layer formedtherein may provide improved feature coverage. For example, thedeposition system 100 may provide for thick coverage at the bottom ofnarrow trench features and good sidewall coverage. The resputteringprocess may use the metal ions to improve the sidewall coverage whilelimiting profile damage.

FIG. 2 is a flowchart of a method 200 of depositing a material layer ona semiconductor wafer. As illustrated, the method 200 includes severalenumerated steps. However, embodiments of the method 200 may includeadditional steps before, after, in between, and/or as part of theenumerated steps. The illustrated embodiment of method 200 begins instep 202 in which a wafer is positioned on a wafer pedestal below acollimator formed from a material and below a target. In step 204, thecollimator is used as a sputtering target in a deposition process. Thedeposition process uses the collimator to provide the material for thematerial layer. In step 206, the deposition process is terminated.

To better describe the method 200, reference is made herein to thedeposition system 100 of FIG. 1. For example, the wafer pedestal 110 isused to position the wafer 108 in the bottom of the chamber 104, belowboth the collimator 106 and the target 114, which is attached to thetarget carrier structure 112. The control system 140 directs at leastone of the DC power supply 124 and the RF power supply 126 to supplyelectrical power to the collimator 106. This causes the collimator 106to function as a target such that material from the collimator is freedand then condenses on the wafer 108 by ions formed within a plasma.

In some embodiments, the collimator 106 and the target 114 may be usedin a deposition process. In such embodiments, the collimator 106 and thetarget 114 may be used simultaneously as a target or the collimator 106and the target 114 may be used sequentially in depositing a materiallayer. This may include supply RF power and/or DC power to the target114 during the deposition process.

When a desired amount of material is deposited onto the wafer 108, thedeposition process may be terminated. In order to improve the sidewallcoverage of features, such as trenches, that are present on the wafer108, a metal ion etch process, or resputtering process, may be startedby the control system 140. As part of the metal ion etch process, thepower supplies 124 and 126 coupled to the collimator 106 may be turnedoff so that no power is applied thereto. Instead, DC power is applied tothe target 114 by the DC power supply 120, which is coupled to thetarget carrier structure 112. During the resputtering, an RF bias ofgreater than 500 W is applied to the wafer pedestal 110, while an RFbias of less than 500 W is applied during the deposition.

The steps of the method 200 are performed in a single deposition chamberthat is part of the deposition system 100. The dual-mode depositionsystem may provide improved coverage at the bottom and on the sidewallsof features having critical dimensions of about 20 nanometers or less.The profile of the material layer may be generally maintained by the useof the metal ions during the resputtering process.

In one exemplary aspect, the present disclosure is directed to amaterial layer deposition chamber. The deposition chamber includes aconfinement shield structure, a wafer pedestal configured to support atleast one wafer within the confinement shield structure, and a targetcarrier structure positioned above the wafer pedestal at an oppositeside of the confinement shield structure. The target carrier structureis configured to support a sputtering target. The deposition chamberfurther includes a collimator disposed within the confinement shieldstructure between the wafer pedestal and the target carrier structurewith an electrical power source coupled to the collimator to supplyelectrical power.

In another exemplary aspect, the present disclosure is directed to amaterial layer deposition system. The material layer deposition systemincludes a wafer pedestal configured to support at least one waferwithin a confinement shield structure and a target carrier structurepositioned above the wafer pedestal at an opposite side of theconfinement shield structure. The target carrier structure is configuredto support a sputtering target. The material layer deposition systemfurther includes a collimator disposed within the confinement shieldstructure between the wafer pedestal and the target carrier structure,an electrical power source coupled to the collimator to supplyelectrical power, and a control system configured to control theelectrical power source coupled to the collimator.

In yet another exemplary aspect, the present disclosure is directed to amethod of depositing a material layer on a semiconductor wafer. Themethod includes steps of positioning a wafer on a wafer pedestal below acollimator formed from a material and below a target, of using thecollimator as a sputtering target in a deposition process, andterminating the deposition process. The collimator provides the materialfor the material layer.

The foregoing outlines features of several embodiments so that those ofordinary skill in the art may better understand the aspects of thepresent disclosure. Those of ordinary skill in the art should appreciatethat they may readily use the present disclosure as a basis fordesigning or modifying other processes and structures for carrying outthe same purposes and/or achieving the same advantages of theembodiments introduced herein. Those of ordinary skill in the art shouldalso realize that such equivalent constructions do not depart from thespirit and scope of the present disclosure, and that they may makevarious changes, substitutions, and alterations herein without departingfrom the spirit and scope of the present disclosure.

What is claimed is:
 1. A physical vapor deposition system comprising: atarget; a collimator; a power source system configured to supply powerto the collimator and the target; and a control system configured tocontrol the power source system, such that the collimator is bombardedwith noble gas ions during a sputtering process and the target isbombarded with metal ions during a re-sputtering process, wherein thecollimator functions as a sputtering target during the sputteringprocess and as the collimator during the re-sputtering process.
 2. Thephysical vapor deposition system of claim 1, wherein the noble gas ionsinclude argon and the metal ions include copper.
 3. The physical vapordeposition system of claim 1, wherein the power source system includes:a radiofrequency (RF) power source coupled to the collimator; a directcurrent (DC) power source coupled to the target; and wherein the controlsystem is further configured to set the power source system to supply RFpower to the collimator via the RF power source during the sputteringprocess and supply DC power to the target via the DC power source duringthe re-sputtering process.
 4. The physical vapor deposition system ofclaim 1 configured to generate a plasma that includes the noble gas ionsduring the sputtering process and the metal ions during there-sputtering process, and further wherein the power source system isconfigured to control the plasma by supplying the power to thecollimator during the sputtering process and supplying the power to thetarget during the re-sputtering process.
 5. The physical vapordeposition system of claim 4, further comprising at least one magnetconfigured to control the plasma.
 6. The physical vapor depositionsystem of claim 1, further comprising a wafer pedestal configured tosupport the wafer, wherein the power source system includes aradiofrequency power source coupled to the wafer pedestal, and furtherwherein the power source system is configured to supply a firstradiofrequency bias to the wafer pedestal via the radiofrequency powersource during the sputtering process and a second radiofrequency bias tothe wafer pedestal via the radiofrequency power source during there-sputtering process, wherein the first radiofrequency bias is lessthan the second radiofrequency bias.
 7. The physical vapor depositionsystem of claim 1, further comprising a pressure system in communicationwith the control system, wherein the pressure system is configured tomaintain a first pressure in the physical vapor deposition system duringthe sputtering process and a second pressure in the physical vapordeposition system during the re-sputtering process, wherein the firstpressure is greater than the second pressure.
 8. The physical vapordeposition system of claim 1, wherein the target and the collimatorinclude a same material.
 9. A physical vapor deposition systemcomprising: a copper-containing target; a copper-containing collimator;a power source system configured to supply power to thecopper-containing collimator and the copper-containing target; and acontrol system configured to control the power source system, such that:during a sputtering process, the copper-containing collimator isbombarded with ions when no power is supplied to the copper-containingtarget, and during a re-sputtering process, the copper-containing targetis bombarded with ions when no power is supplied to thecopper-containing collimator.
 10. The physical vapor deposition systemof claim 9, wherein the copper-containing collimator is bombarded withargon ions and the copper-containing target is bombarded with copperions.
 11. The physical vapor deposition system of claim 9, configured togenerate a plasma that includes the ions during the sputtering processand the ions during the re-sputtering process, and further wherein thepower source system is configured to control the plasma by supplying thepower to the copper-containing collimator and the copper-containingtarget.
 12. The physical vapor deposition system of claim 11, furthercomprising at least one magnet configured to control the plasma.
 13. Thephysical vapor deposition system of claim 9, wherein thecopper-containing collimator includes a copper-containing layer disposedover an interior core.
 14. A method comprising: positioning a wafer in aphysical vapor deposition system that includes a collimator disposedbetween the wafer and a target; during a sputtering process in thephysical vapor deposition system, bombarding the collimator with noblegas ions, thereby causing material from the collimator to condense onthe wafer; and during a re-sputtering process in the physical vapordeposition system, bombarding the target with metal ions, therebycausing material from the target to remove a portion of the condensedcollimator material on the wafer.
 15. The method of claim 14, whereinthe noble gas ions include argon and the metal ions include copper. 16.The method of claim 14, further comprising supplying radiofrequencypower to the collimator during the sputtering process and direct currentpower to the target during the re-sputtering process.
 17. The method ofclaim 16, further comprising supplying direct current power to thecollimator during the sputtering process.
 18. The method of claim 14,further comprising turning power to the collimator on and power to thetarget off during the sputtering process and turning the power to thecollimator off and the power to the target on during the re-sputteringprocess.
 19. The method of claim 14, further comprising maintaining afirst pressure in the physical vapor deposition system during thesputtering process and a second pressure in the physical vapordeposition system during the re-sputtering process, wherein the firstpressure is greater than the second pressure.
 20. The method of claim14, wherein the physical vapor deposition system further includes awafer pedestal configured to support the wafer, the method furthercomprising applying a first radiofrequency bias to the wafer pedestalduring the sputtering process and a second radiofrequency bias to thewafer pedestal during the re-sputtering process, wherein the firstradiofrequency bias is less than the second radiofrequency bias.